In the past ten years, with the great increase in World Wide Web (Web) systems, the computer processing power required by an organization has grown exponentially each year so that now hundreds, and even thousands, of servers are required. This has led to a resurgence of larger and larger mainframe computers; particularly mainframe and like large computers operating in a virtual machine (VM) mode in which multiple instances of an operating system and associated application program reside on the same physical hardware.
Such virtual machines have been satisfying the needs for the large number of operating instances and applications that are often arrayed as virtual machine server farms in which the virtual machines reside on a number of physical servers. For further background, attention is directed to the article: Virtual Linux servers under z/VM: security, performance, and administrative issues, D. Turk, published in the IBM Systems Journal, July 2005; and to the article, More POWER to Ya, Expanded Virtualization Manager capabilities help customers grow and manage virtualized environments, Jim Fall, published in the IBM Systems Magazine, September 2007. In such virtual machine environments, wherein multiple user computers are connected to each physical virtual machine platform providing a plurality of virtual machines respectively connected to these multiple users at client computers and computer controlled devices, power management is difficult to control. Full power is required at each virtual machine platform prior to the initiation of a virtual machine session. Since the virtual machine platform must always be available to remote user computers that need to access appropriate virtual machines, it has been customary to continuously operate any on-line platform in a full power mode. The wasted power consumption becomes particularly pronounced when the virtual machine platforms are arrayed as virtual machine server farms consisting of a number of physically powered servers.